Maternal-fetal inflammation affects Cdh1/E-cadherin epigenetic regulation and craniofacial development

Cleft lip with or without palate (CLP) is a multifactorial trait associated with environmental exposures such as smoking, alcohol consumption, and pro-inflammatory conditions during early pregnancy, as well as with both common and rare genetic variants. Our group identified CDH1 loss-of-function variants segregating in families with CLP, with incomplete penetrance linked to promoter hypermethylation. Previously, we demonstrated that gene-environment interactions driven by pro-inflammatory factors can induce this methylation, downregulate E-cadherin expression, and impair neural crest migration, thereby contributing to the etiology of CLP. However, the embryonic consequences of the two-hit CLP model (CDH1 haploinsufficiency combined with pro-inflammatory insult) have not yet been explored in mammals. Here, under single dose of floxed-Cdh1, we investigated the pro-inflammatory response at the maternal-fetal interface, its impact on cytokine and Cdh1 expression along the anteroposterior axis, the associated epigenetic landscape in the embryonic head, and the effect on cranial structures. We found that pro-inflammatory activation differentially signals to the embryo between anterior and posterior regions, impairing Cdh1/E-cadherin expression in NC cells of the head, accompanied by Cdh1 promoter hypermethylation and other differentially methylated genes involved in cell-junction maintenance. Our findings support a model in which maternal pro-inflammatory responses act as environmental factors that repress NC CDH1 expression through epigenetic mechanisms, contributing to CLP development by downregulating E-cadherin and potentially compromising overall epithelial integrity. Animal Ethics Committee (CEUA IB/USP) number approval: 394/2022